The present invention relates to a new and improved construction of papermaking machine.
In its more specific aspects the present invention relates to a new and improved papermaking machine comprising at least one dewatering means, for instance a wire or sieve or the like, for forming a fiber web or ply and at least one headbox for infeeding a fiber stock suspension which is to be applied to the dewatering wire or the like. The fiber stock suspension is discharged from the headbox through an outfeed slice or gap which extends across a predetermined operating or working width of the headbox. At least one deflecting means or device is provided for separating and taking-up a partial stock flow or stream at a related marginal zone or region of the operating width from a main flow of the fiber stock suspension. Such deflecting means can be introduced into the flow path of the fiber stock suspension between the impact location of the stock fiber suspension at the dewatering wire and the outfeed slice or gap of the headbox.
In a papermaking machine as known, for example, from U.S. Pat. No. 3,361,620, the headbox is directed towards a longitudinal wire and comprises a guide plate extending from the outfeed slice or gap to a location close to the longitudinal wire. The fiber stock suspension flows over this guide plate to the impact or run-on location. In this known papermaking machine the deflecting means or device contains two withdrawal channels which are placed upon the guide plate at the two marginal regions. Each of these withdrawal or discharge channel comprises an inlet opening extending opposite to the outfeed slice or gap, an inlet section which extends substantially in the travel or running direction of the longitudinal wire, and a deflecting section which follows the inlet section on the downstream side thereof and which is laterally extended beyond the margin or edge of the longitudinal wire. The known deflecting means or device requires a relatively large installation space at the region of the papermaking machine which follows downstream of the headbox, in order to positively catch the partial flow or stream of the fiber stock suspension which is to be entrapped and to remove the same from the marginal region. Therefore, the state-of-the-art deflecting means is unsuited for papermaking machine designs having narrow or cramped spatial conditions at the region of the headbox, and particularly cannot be arranged between two converging dewatering wires or the like. The reason therefor is that the cross-section or throat area available for the withdrawal of the excess fiber stock suspension decreases as seen in the direction of flow. Thus, the withdrawal of the arriving amount of fiber stock suspension can be impaired by an apparatus of the known design, for instance in the case of an increased width of the partial flow or stream which is to be separated.